This invention relates to the filed of rivets and their forming, and more particularly to tubular rivets, methods and tools suitable for fastening fiber reinforced plastic laminates to one another or to metal. The use of rivets to fasten fiber reinforced plastic laminates, for example those using glass, graphite, or boron fibers has incurred a recognized problem of stress crazing resulting from the formation or setting of a rivet head, particularly, but not exclusively, in use of blind-formed rivets in which a bulbous head is typically formed on the blind side.
U.S. Pat. No. 4,221,041 to G. Hufnagl et al discloses a semi-tubular rivet with conical heads used in fastening fiber reinforced laminates which have been previously countersunk. The rivet described in that patent requires access from both sides of the work.
The problem of undue and damaging stresses being set up during the setting of rivets in laminates of the type concerned is magnified when one or both of the laminate exterior surfaces are not normal to the axis of the preformed rivet hole and the principal axis of the rivet.